Validity of heart-rate based measurements of oxygen consumption during work with light and moderate physical activity.

For ergonomic purposes it is useful to quantify the energy expenditure and the level of physical activity imposed on workers. Oxygen consumption (VO₂) is often used to calculate energy expenditure and can be used as an indication of physical activity. Twenty-five subjects participated in the study. Oxygen consumption (VO₂) in L O₂/min and heart-rate (HR) in beats per minute (bpm) were simultaneously measured during different work tasks at each individual's workplace. Ninety-one different work tasks with light or moderate physical activity were included (physical activity was classified by the VO₂ measurements). Estimated oxygen consumption (L O₂/min) was then calculated by using the HR measurements in bpm combined with individual HR-VO₂ equations established in a laboratory. Although heart-rate based estimations of individual oxygen consumption showed relatively low precision, heart-rate measurements in combination with individual exponential HR-VO₂ equations can be used to discriminate between work involving light physical activity and work involving moderate physical activity.